Colloidal silica is composed of ultra fine silicon dioxide particles dispersed in water/solvent. It could generate super dirt pick up resistance (DPUR), hardness, stain blocking, etc for the dried/cured paint film. Colloidal silica dispersions have been used for a long time, e.g. as a coating material to improve adhesive properties as well as increasing wear and water resistance of various materials. However, these dispersions, especially highly concentrated colloidal silica dispersions, are liable to gelling or precipitation of silica, which makes longer storage impossible.
U.S. Pat. No. 7,544,726B2 disclosed a method of producing a stable substantially aqueous silanized colloidal silica dispersion having a silica content of at least about 20 wt % comprising mixing at least one silane compound and colloidal silica particles, wherein the weight ratio of silane to silica is from about 0.003 to about 0.2, preferably from about 0.006 to about 0.15, and most preferably from about 0.015 to about 0.1. This method is complicated and with high cost.
It is therefore, still desired in the art to get to a novel aqueous coating composition, especially, aqueous coating composition that has better stability comparing to prior art colloidal silica comprising coatings.